Drop forge press or the like with a pressure medium drive



H. BCHE July 25, 1967 DROP-FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE 5 sheets-sheet 1 Filed Oct. l5, 1963 H. BCHE:

July 25, 1967 DROP FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Filed oct. 15, 1963 H. BCHE July 2.5, 1967 DROP FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Filed Oct. l5, 1963 5 Sheets-Sheet 5 /M/fA/Am/Pr www H. BcHE July 25, 1967 DROP FORGE PRESS 0R THE LIKE WITH A PRESSURE MEDIUM DRIVE 5 Sheets-Sheet 4 Filed Oct. l5, 1965 IIIIIIIIII] July 25, 1967 H. BCH 3,332,273

DROP FORGE PRESS 0R THE LIKE WITH A PRESSURE MEDIUM DRIVE Filed Oct. l5, 1963 5 Sheets-Sheet 5 Y /l/Vfp i United States Patent Oiiice 3,332,273 Patented July 25, 1967 3,332,273 DROP FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Hans Bch, Gardelenbergstrasse 29, Huckeswagen, Rhineland, Germany Filed Oct. 15, 1963, Ser. No. 316,373

Claims priority, application Germany, Oct. 15, 1962,

B 69,234 2 Claims. (Cl. 72-453) This invention relates to presses for forging or stamping metallic bodies or for other treating operations, and particularly to such forging presses or the like, in which the tup is connected to a piston actuated by a liquid pressure medium. v

Similar forging presses or the like so far known have an essential disadvantage which render-s them unsuited for much forging work, i.e. a too low speed of the tup piston during the pressing stroke and the return stroke. Therefore, the `blank heated-up for the forging operation cools down comparatively quickly, which complicates the workability and, furthermore, leads to an overheating and quick wear of the forging dies. i

An essential object of the invention extends to the provision of an hydraulically operated forging press or the like, in which the aforesaid disadvantages are avoided.

In short, the new Working principle Iof the forging press according to the present invention consists of communicating a fluid pressure medium in a cylinder to ar driving mass before beginning the pressing operation that kinetic energy which is imparted essentially represents the working power of the press. The liuid pressure medium may be gaseous, vaporous or liquid; the driving mass comprises a twin-piston, differential piston or the like received in the cylinder. The movement of the driving mass is transferred by a separate uid medium to the pressing tup shaped as a piston or, alternatively, a pressing tup firmly connected to la piston.

The forging press according to the present invention provides an acceleration of the driving mass (driving piston and plunger piston) in `a manner such that it attains the desired end speed within a few tenths of a second by transferring the movement with the help of uid medium valves, long pipelines or by-passes and high speeds with consequent seepage loss of the hydraulic transfer medium. The press according tothe present invention, therefore, operates much more quickly than the hydraulic forging lpresses so far known and the contact of the dies with the heated-up blank is much shorter than in the presses already known.

The drawings represent different embodiments preferred on the invention, i.e.

FIG. 1 shows a vertical section and, partly, a side elevation of the forging press as per invention, in which a gaseous or vaporous pressure medium is used for drive,

FIG. 2 a forging press as per invention with, partly, a side elevati-on and, partly, with a sectional view, in which an hydraulic pressure medium is used for driving purposes,

FIG. 3 shows a top view of the upper part of the forging press as per FIG. 2,

FIG. 4 shows a vertical section through the upper part of the forging press as per FIG. 2,

FIG. 5 is a side elevation, partially in section, of another embodiment wherein a die moves upwardly;

FIG. 6 is a section along lines VI-VI of FIG. 5;

FIG. 7 is a plan view of the apparatus of FIG. 5; and

FIG. 8 is a front elevation of the apparatus of FIG. 5.

The forging press represented by FIG. 1 is equipped with a frame a which with its base a' is fixed to the floor in a suitable way.

The frame a is provided with a recess, in which the bottom die UG is located. At the upper end, the frame a forms a cylinder a", in which the piston-like extension d of the pressing tup d is slideable .which carries the top die OG.

rlflhe pressing tup is provided with lateral extensions d, with which the tup is slidea'bly guided at the guidesurfaces x of the frame.

In the cover a" of the cylinder a a cylindrical hollow space A is recessed with its axis identical to that of the hollow space of cylinder a. The extension c of a driving piston c', which is plunger-shaped extends into the hollow space A. The term plunger shaped is used herein to dene an elongated rod having uniform diameter therealong leading to an end face.

In the prolongation of the hollow space A and with identical axis a hollow space. d" is provided in the tup piston d.

The driving piston c is arranged in a cylinder b fixed to the flange -of the cylinder cover a.

The cylinder space C over the driving piston c cornrnunicates, by a channel in the wall of cylinder b, with a control valve S (schematically shown), to which at DM is connected the supply line, not shown, for a gaseous or vaporous pressure medium.

Beside the forging press there is a tank OB for a hydraulic medium, e.g. for hydraulic oil. In this tank, for instance, an oil pump g is arranged which is driven by a motor (not shown) and connected, by the pipeline g' and across the nonreturn valve h, to an opening g in the cylinder a", which opening leads to the hollow space d. The nonreturn valve lz is so constructed that, lby a spring, it is kept firmly on its seat thus shutting the channel g, while the valve is opened by the pressure medium flowing through the pipeline g'.

Off the hollow space A yand at a point z situated a bit below the underside of the plunger piston c in its upper home position departs a pipeline g leading to the tank OB as a return pipe.

At both sides of the cylinder b, two cylinders e are placed on brackets e. The pistons e" of the cylinders e communicate each with a piston rod f which extend through openings f into the inner of the frame a and, by means of buffer f" each, attach at the lower side of the studs d" of the pressing tup d.

At the lower end, i.e. at DM, the cylinders e are each connected to a supply line (not shown) for a gaseous or vaporous Ipressure medium, preferably compressed air.

The cylinders e and the pistons e are so dimensioned that at a given pressure of compressed air or the like on the underside of the pistons e they lift the pressing tup d and the plunger piston c together with the driving piston c to the original position as shown in FIG. 1 of the drawing.

At the first start-up of the press represented, the hollow space d' of the tup d and the hollow space A of the frame part a" -must be filled, primarily, with a suitable hydraulic liquid, e.g. oil. The oil to be used is -fllled into the tank OB `and then pumped into the hollow spaced d'" by means of pump g and pipeline g after compressed air or the like has been previously admitted to the cylinders e. The oil pumped by the pump g then presses the plunger piston c upward until this reaches into the upper end position as shown in FIG. l. The oil then returns to the tank OB through the opening i and the pipeline g'".

When by operating the control Valve S with the help of a customary foot or hand lever (not shown) a lgaseous pressure medium, e.g. compressed air, is admitted to the cylinder space C above the driving piston c', the driving piston c' is moved downward together with the plunger piston c. At this moment, the opening i is closed and with the further movement of the plunger piston c the pressing tup d is moved downward as the filling of the hollow spaces d, A does not change its volume, since oil is neither entering nor leaving the spaces d, A and the oil pressure within the spaces d, A is not substantially increased. The pressing tup d, plunger piston c and driving piston c now jointly continue moving downward, i.e. they continue the pressing stroke until the top die OG sits upon the bottom die UG.

When the cylinder space C over the driving piston c is relieved the pressing tup d, plunger piston c and driving piston c', by the effect of the pistons e" fed with cornpressed air at their underside, move upward until the elements reach again into the original position as shown in FIG. 1. Should, for instance, because of leakage, the plunger piston c not have entirely reached into the original position and keep the opening i closed, it is lifted by the pressure oil pumped by the pump g into the spaces d", A until the opening is free and the oil is allowed to circulate through the pipelines g', g

It is advantageous to construct control valve S in the way already known, i.e. in such a manner that the supply of the pressure medium DN to the cylinder space C is interrupted already after a partial stroke of the piston c with a View to obtaining a favorable expansion chart when the piston c moves downward. This can be effected, for instance, by influencing the control valve S from, alternatively, the piston c', piston rod or plunger piston c, or by actuating the control valve S according to a previously fixed program. Such a control valve for the pressure medium admitted to the cylinder space C is of great advantage for the quick return to their original position of the tup d and the plunger piston c together with its driving piston c'. When the forging press is operated under lfull pressure in the upper cylinder space C during the Working stroke, the expansion time then required by the filling would delay the return stroke of the pressing tup and of the pistons c.

The driving mass consisting of the piston c' and the plunger piston c is accelerated when moving downward, and the speed attained by this mass at the end of the pressing stroke represents, in combination with the mass, the output of the press. The attainable size of the pressing force, in itself, depends only on the size of the retardation way which is affected by the pressing operation on the blanks put between the dies OG, UG under consumption of the kinetic energy of the driving mass c, c. In other words the amount of kinetic energy remaining in the driving mass for transmission to the die UG depends on the extent to which energy is absorbed by the blanks in being deformed. It is, however, convenient to limit the maximum size of the pressing force in order not to imperil the press during operation. For this purpose, a channel SV can be provided in the wall of cylinder a leading to -a safety valve (not shown) which does not permit the pressure of the oil filling in the hollow spaces d", A to exceed a determined value.

At a definite stroke of the pressing tup d of, e.g., h2 (FIG. 1), the stroke h1 of the driving piston c' depends on the ratio cross section F1 of plunger piston c to cross section F2 of tup piston d.

The ratio F11F2, however, is also important for the pecularity of the press according to the present invention as can be seen from the following illustrative example.

A press having a pressing force of 1000 tons and a working power of 5000 mkg., for instance, shows a ratio of F1:F2=1:8. At a given stroke for the pressing tup d of h2=200 mm., the stroke of the driving piston c will then be h14=8.h2=1600 mm. The following figures for this press are surely of interest:

Weight of the driving mass c, c'=500 kg., vmax-=13 m./sec., pmax-=600 atm.

As the pressing tup d is supported only by the surface FZ-Fl in the press frame a, part of the kinetic energy of 5000 mkg. of the driving mass c, c is transferred as alternatively, pressing or Working energy to the press 800=625 mkg.

or, respectively,

E8= 125 tons That is negligible when compared with an equally capable forging hammer.

During the pressing stroke, the oil pump g cannot pump through the pipeline g as the nonreturn valve lz is kept closed by the high pressure existing in the hollow space d. During this time, the pressure oil can return to oil tank OB through an overflow valve V so that the pump g is not imperilled.

During the return stroke of the elements d, c, c an intake of pressure oil into the hollow space d" is of no importance, because after the plunger piston c has reached its original position the entering oil volume may run into the tank OB through the opening i.

It is important to start the press only when the driving piston c together with its plunger piston c keep their original position as shown in the drawing. This can be assured by using, e.g., the quantity of pressure oil returning to tank OB through opening i and pipeline g" in order to release an equipment locking the control value S. The invention, however, is not limited to this embodiment.

Should the relative safety devices fail, a buffer k, made, e.g., of copper and arranged on the cylinder cover a" absorbs, without any danger, the energy of the driving piston c impacting on it if, eg., the oil level in the hollow low space d" of the pressing tup d had lowered too much.

The press shown in FIG. 1 is distinguished by a simple and clear design. The press has only a few moved parts and little friction loss when in operation. The interposition of the hydraulic power-transferring means in the hollow spaces d", A permits of installing a safety valve SV which allows the press force to be kept under the permissible maximum.

The embodiment of the invention shown in FIGS. 2 to 4 of the drawing is a drop-forging press that is actuated by a uid pressure medium, e.g., pressure oil. Such a hydraulic pressure medium can be brought to a very high pressure, e.g., about 200 atm. gauge by comparatively simple means. The employment of a pressure medium under so high a pressure brings essential advantages in the design and performance of the forging press.

As can be seen already from FIG. 2, the driving cylinder b can be made with a considerably smaller diameter. Besides it is possible, as shown in FIG. 4, to provide the plunger piston c with an axial bore c", into which suitably extends a pipe l long fixed in the cylinder cover m and open at its lower end. Below, the bore c" is closed by a plug c".

In this embodiment, the outer cylinder b serves still solely for guiding the shoulder c' of the plunger piston c.

As the diameter of the cylinder b has been considerably diminished it is possible-as shown in FIGS. 2 and 4-to accommodate on the cylinder part a of the press frame a all equipment for the hydraulic drive and the control valve in a case n.

The case includes the following elements:

The driving motor, e.g., an electric motor o coupled directly to a multicylinder oil pressure pump p. The pressure pump p communicates through the conduit q with a tank q for hydraulic oil. The pressure oil brought to a high pressure in the pump p flows, through the conduit r, to the collecting main s, to which several pressure oil accumulators t, eg., of the Mercier-Greer type are connected.

Connected to the collecting main is, furthermore, the control valve case u which is also connected to a foot or hand lever not shown. When, e.g., the foot lever of the control valve is pushed down, the communication between the collecting main s and the conduit 1 is established so that oil under high pressure, through conduit 1 and subsequent conduit 1 (FIG. 4) may flow to the axial bore c of the plunger piston c. The plunger piston c then moves downward. When it reaches its lower end position, the control valve u is shifted so that the conduit 1 may communicate with the oil conduit v which, as per FIG. 3, leads to the oil tank q, in which is collected the expanded pressure oil expelled out of the hollow space of cylinder c". During this time, the communication between the conduit 1 and the collecting main s is interrupted, so that the oil under high pressure formerly produced by the pressure pump p is collected in the accumulators t.

As can be seen, the drive of the forging press, when using oil under high pressure, or another hydraulic pressure fluid, is of much simpler design than when using, e.g., compressed air (6-7 atm.) as a driving means.

The control of expansion required when driving a press by gaseous pressure media with a view to obtaining a good economy of operation entails in heavy presses with a driving cylinder of more than 1 m. in diameter considerable costs for the valve timing. 'Ihe supply of the compressed air required is also costly. Heavy pressure-resistant pipes must be laid and a pressure-resistant air vessel and, circumstances permitting, an equipment for heating-up the compressed air must be provided for. Nevertheless, it is not possible to reach a total eiciency of more than 40- 50% in forging presses driven by gaseous pressure-media.

The hydraulic drive as per FIGS. 2-4 of the drawing is comparatively much more advantageous. There is neither detrimental compression heat nor imperfect expansion. The supply lines and pressure accumulators are comparatively small. The total eiciency rises up to about 65- 70%.

The installation of the equipment for producing vand controlling the hydraulic pressure medium on the frame o the forging press has the special advantage that the pressure medium lines between the different apparatuses can be made very short. This is of great importance in view of the advantageous high speeds of the driving piston of the forging press (12 m./sec.). It has also to be considered that a drop 'forging press must operate at substantially higher speeds of pistons than a conventional free-shaping forging press.

With the embodiment as per FIG. 2, the return cylinders e are arranged near the bottom plate a' of the press frame a. The pistons e communicate with the trip d by pressing rods f and buffers f".

For the rest, the design of the frame a, pressing'piston d" and cylinder a is the same as described in FIG. 1.

As a rule, it is convenient to keep as small as possible the Volume of the hydraulic medium serving for the transfer of energy from the driving piston to the pressing piston in order to diminish t-he inuence of the compressibility of the hydraulic medium. Circumstances permitting, it is, therefore, advantageous to omit in the case of embodiment as per FIGS. 1 and 2 the hollow space d" provided for in the tup piston d', into which the driving piston c plunges and, instead of this, to augment the height of the cylinder part a". However, a disadvantage can then be the overall height of the press.

FIG. 5 shows another embodiment of the invention avoiding a larger size of the press.

With the embodiment as per FIG. 5, the pressing piston 50 carrying the tup 51 and the one die 52 is so arranged in the cylinder 53 of the press frame 54 that it moves upwards when striking. The other die 55, in this case, is arranged in the crosshead 56 of the press frame kept by two supports 57. Beside the press plunger cylinder 53 there is arranged, in the frame, the cylinder 58 for the driving piston 59. Cylinder 5'8 and cylinder 53' are connected, below, by a channel 60.

In this case, the design of the driving piston is the same as in the embodiment as per FIGS. 2-4. Thus, the driving piston, e.g., is driven by a Huid pressure medium.

I-f for any reas-on the iilling of the cylinder 58 has grown too small, the driving piston 59 is lbraked in the conical extension 61 of the cylinder 58.

As the weight of the pressing tup 51 together with piston 50, generally, is not sufficient for lifting the driving piston 59, after the pressing operation, into the original position as per FIG. 5, as can be seen from FIG. 8, two return cylinders 62 are assigned to the tup 51, which, in this case, act as hydraulic cylinders, i.e., after the stroke they move the tup 51 lout of its lifted position again into the original position as per FIGS. S-S. The piston rods 63 of the pistons 64 sliding in the cylinders 62 attack the tup 51 at 65. The cylinders get fluid pressure medium (pressure oil) out of a pressure accumulator 66, e.g., of the Mercier-Greer design.

In the embodiment as per FIG. 5, the drive is arranged in a case 67 on the crosshead 56 of the press frame.

The driving equipment consists of a small oil pressure pump 68 which replaces especially leakage oil.

With the arrangement represented, the return cylinders 62 are permanently fed with pressure oil coming from the pressure accumulator 66. This arrangement has the advantage that at the high position of the pressing tup 51, i.e. immediately after the pressing operation, the pressure in the accumulator 66 is highest. After the pressing operation, the pressing tup is, therefore, lifted from the treated work-piece with considerable force and quickly brought again into its original position. Thus, the pressure in the accumulator 66 is lowest when the pressing Itup 51 keeps its lowest position and the driving piston 59 is lifted.

To the driving equipment still Ibelongs the driving motor 69 which produces the pressure medium for the driving piston 59 in the pressure pump 70. Besides the pressure pump the storage vessel for cooled oil 71 is provided for, from which the suction line 72 leads to pump 70. The delivery line 73 runs to the pressure accumulator 74 and from there to the control valve 75, the outlet connection of which, through conduit 78, communicates with the inner tube 79 of the driving piston 59.

When reversing the control gear the oil flows back to the storage tank through conduit 80.

What I claim is:

1. A press for drop-forging or stamping metallic bodies or the like comprising: means dening a cylinder having a larger diameter segment and a smaller diameter segment, a piston slidably received in said cylinder larger diameter segment; a pressing tup connected to said piston and projecting therefrom out of said cylinder through one end of the cylinder, said piston comprising an extension of said pressing tup; said cylinder being constructed and arranged to receive a body of fluid pressure medium therein behind said piston for actuating sliding of said piston; a second piston of smaller diameter than the rstmentioned piston, said second piston being slidingly received in said cylinder smaller diameter segment and having a portion thereof projecting therefrom out of said cylinder through the opposite end thereof from said one end, the sec-0nd piston being constructed and arranged to have substantially the same diameter as said cylinder smaller diameter segment for a substantial distance along said second piston including as much of said second piston as lies within said cylinder smaller diameter segment during operation of said press; said body of uid pressure medium -being received between said pistons; means defining a driving piston cylinder; a driving piston slidingly receive in said driving piston cylinder and secured to said second piston projecting portion; conduit and valve means for admitting a iiuid under pressure to said driving piston cylinder for rapidly accelerating said driving piston and second piston, as a unit, to essentially constitute Working power of the press as kinetic energy lof the driving piston and second piston prior t0 contact of the tup with the metallic body to be operated upon; means defining a reservoir of iluid pressure medium; inlet conduit means communicting between said reservoir and said cylinder; a non-return valve interposed in said inlet conduit means; return conduit means communicating Ibetween said cylinder smaller diameter segment and said reservoir, said return conduit means being in an operative and open communication with said reservoir only when said second piston is relatively Withdrawn from extension into said cylinder smaller diameter segment; and means for continuously pumping fluid pressure medium from said reservoir into said inlet conduit means.

2. The press of claim 1 wherein the driving piston has means defining a central longitudinal bore; and further including a hydraulic pressure medium admission pipe afxed to said cylinder and extending into said bore.

References Cited UNITED STATES PATENTS 1,054,194 2/1913 Gerdav 100-269 1,063,360 6/1913 Larsen 91-399 1,068,243 7/ 1913 Zversen 100-269 1,230,486 6/ 1917 Jacomini 100-269 1,230,492 6/ 1917 Kristufek 100-269 3,063,428 11/1962 Neuman 92--108 FOREIGN PATENTS 122,108 6/ 1948 Sweden.

CHARLES W. LANHAM, Primary Examiner.

G. P. CROSBY, Assistant Examiner. 

1. A PRESS FOR DROP-FORGING OR STAMPING METALLIC BODIES OR THE LIKE COMPRISING: MEANS DEFINING A CYLINDER HAVING A LARGER DIAMETER SEGMENT AND A SMALLER DIAMETER SEGMENT, A PISTON SLIDABLY RECEIVED IN SAID CYLINDER LARGER DIAMETER SEGMENT; A PRESSING TUP CONNECTED TO SAID PISTON AND PROJECTING THEREFROM OUT OF SAID CYLINDER THROUGH ONE END OF THE CYLINDER, SAID PISTON COMPRISING AN EXTENSION OF SAID PRESSING TUP; SAID CYLINDER BEING CONSTRUCTED AND ARRANGED TO RECEIVE A BODY OF FLUID PRESSURE MEDIUM THEREIN BEHIND SAID PISTON FOR ACTUATING SLIDING OF SAID PISTON; A SECOND PISTON OF SMALLER DIAMETER THAN THE FIRSTMENTIONED PISTON, SAID SECOND PISTON BEING SLIDINGLY RECEIVED IN SAID CYLINDER SMALLER DIAMETER SEGMENT AND HAVING A PORTION THEREOF PROJECTING THEREFROM OUT OF SAID CYLINDER THROUGH THE OPPOSITE END THEREOF FROM SAID ONE END, THE SECOND PISTON BEING CONSTRUCTED AND ARRANGED TO HAVE SUBSTANTIALLY THE SAME DIAMETER AS SAID CYLINDER SMALLER DIAMETER SEGMENT FOR A SUBSTANTIAL DISTANCE ALONG SAID SECOND PISTON INCLUDING AS MUCH OF SAID SECOND PISTON AS LIES WITHIN SAID CYLINDER SMALLER DIAMETER SEGMENT DURING OPERATION OF SAID PRESS; SAID BODY OF FLUID PRESSURE MEDIUM BEING RECEIVED BETWEEN SAID PISTONS; MEANS DEFINING A DRIVING PISTON CYLINDER; A DRIVING PISTON SLIDINGLY RECEIVE IN SAID DRIVING PISTON CYLINDER AND SECURED TO SAID SECOND PISTON PROJECTING PORTION; CONDUIT AND VALVE MEANS FOR ADMITTING A FLUID UNDER PRESSURE TO SAID DRIVING PISTON CYLINDER FOR RAPIDLY ACCELERATING SAID DRIVING PISTON AND SECOND PISTON, AS A UNIT, TO ESSENTIALLY CONSTITUTE WORKING POWER OF THE PRESS AS KINETIC ENERGY OF THE DRIVING PISTON AND SECOND PISTON PRIOR TO 